Control units may be used for actuating injection systems for motor control in motor vehicles. These control units may precisely control or regulate the injection quantity and the time of injection within an internal combustion engine. Injection systems of motor vehicles may operate via a system having an injection nozzle and a piezoelectric element which may be actuated by the control unit. The control unit may include a triggering device, a high voltage supply, a direct current converter, a buffer capacitor, and a piezoelectric output stage. The buffer capacitor may supply high voltage to the control unit. The control unit may be connected to the engine control via a cable harness plug-in connector. Control units for piezoelectric elements may operate at elevated voltages which may be considerably higher than a safety extra-low voltage. In contrast to previous systems, such elevated voltages in certain cases may represent an increased safety hazard for personnel. For example, high voltage may still be present in the control unit plug-in connector when the cable harness plug-in connector is disconnected and a hardware error is present inside the piezoelectric output stage for the intended actuation of the peripheral piezoelectric element and of the piezoelectric output stage. Also, high voltage may still be present in some components for a certain time when the battery power supply is disconnected or the control unit is switched off. These conditions may result in hazards to personnel if the control unit plug-in connector is touched, in particular when the control unit is opened and several components still carry high voltage.